Flexible lead surface-mount semiconductor package

ABSTRACT

A diode chip is mounted on two bottom metal leads of a surface-mount package through two flexible links. The links are zigzag cantilevers attached to the metallic plates. The cantilevers serve as springs to support the device and to cushion any temperature stress or bending stress so as not to damage the connection between the device and the metallic leads.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to semiconductor device package,particularly to surface mount optoelectric diode package, such as thatfor a light emitting diode (LED), a laser diode (LD), a photo diode(PD), etc. The invention is also applicable to a light sensor diode,such as a image sensor. The invention may also be applicable to packagesfor other non-optoelectric semiconductor devices.

[0003] 2. Brief Description of the Related Art

[0004]FIG. 1 shows a prior art optoelectric diode package. Asemiconductor chip 10 is mounted on two metallic plates 11, 12 servingas extension leads for a surface-mount diode package. The chip 10 issealed in glue 13 for protection. FIG.2 shows the side view of thepackage. The outer portions of the metallic plates 11 and 12 are notcovered with glue 13. The bottoms of the exposed portions L, R arecontact surfaces for surface mounting to a motherboard. When thetemperature changes, the motherboard may bend, causing the device chip10 to break away from the metallic plates 11, 12. Then, the diode cannotfunction.

[0005] Another occasion for the device chip 10 to break away themetallic plates 11,12 occurs when the diode package is mounted on acurvilinear motherboard such as a display panel. The curving of thesurface can also cause bending stress on the device to damage thedevice. An example of such a situation occurs when a decorative lightemitting ribbon is mounted at the corner of an automobile body.

[0006] Still another occasion occurs for the keys of a computer keyboard. Sometimes, the keys are lit with a light emitting diodes for easyrecognition in the dark. Due to constant pounding the keys, the lightemitting devices may dislodge from the leads.

SUMMARY OF THE INVENTION

[0007] An object of the present invention is to prevent an optoelectricdevice from breaking away from the leads of a surface mount package dueto temperature stress. Another object of this invention is to prevent asemiconductor device from breaking away from the leads of surfacemountpackage due to bending stress.

[0008] These objects are achieved by mounting a semiconductor chip toits bottom metal leads for surface mounting through two flexible links.The links are zigzag cantilevers attached to the metallic plates. Thecantilevers serve as springs to support the device and to cushion anytemperature stress or bending stress so as not to damage the connectionbetween the device and the metallic leads.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009]FIG. 1 shows the top view of a prior art package for surfacemounting a diode chip to a motherboard.

[0010]FIG. 2 shows the side view of FIG. 1.

[0011]FIG. 3 shows the top view of diode package with two horizontalzigzag cantilevers based on the present invention.

[0012]Fig. 4 shows the side view of Fig. 3.

[0013]FIG. 5 shows the top view of a second embodiment of the packagewith two inverted V-shaped horizontal cantilevers.

[0014]FIG. 6 shows the side view of FIG. 5.

[0015]FIG. 7 shows the top view of a third embodiment of a package withtwo vertical cantilevers.

[0016]FIG. 8 shows the side view of FIG. 7.

[0017]FIG. 9 shows the top view of a fourth embodiment of a package withtwo horizontal zigzag cantilevers for packaging a diode with a topelectrode and a bottom electrode.

[0018]FIG. 10 shows the side view of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

[0019]FIG. 3 shows the top view of the first embodiment of diode packagebased on the present invention. A diode chip 20 is mounted on twometallic plates 21, 22. The metallic plates 21 and 22 have a rectangularcut 25 in the middle portion to form two horizontal zigzag cantilevers.The cantilevers serve as springs. When the package is subject totemperature variations, the spring action of the zigzag cantilevers cancushion the expansion and contraction stress. The chip 20 is sealed inglue 23 up to a portion of the zigzag cantilevers as shown in side viewFIG. 4. The bottoms of the unsealed portions L1 and R1 of the metallicplates 21, 22 serve as contacts for surface mounting the package to amotherboard.

[0020]FIG. 5 shows the top view of a second embodiment of thisinvention. The diode chip 20 is mounted on two metallic plates 31, 32 asin FIG. 3. However the cut 35 in the metallic plates 31, 32 is ofinverted V-shape (instead of being rectangular) to form the zigzagcantilevers. Otherwise the function of zigzag cantilevers are the sameas in FIG. 3. The chip 20 is sealed in glue 23 up to a portion of thezigzag cantilevers. FIG. 6 shows the side view of FIG. 5, correspondingto FIG. 4. The bottoms of the unsealed portions L2 and R2 of themetallic plates 31, 32 serve as contacts for surface mounting thepackage to a motherboard.

[0021]FIG. 7 shows the top view of a third embodiment of the presentinvention. The diode chip 20 is mounted on two metallic plates 41, 42.The metallic plates are bent to form two two vertical zigzag cantilevers45. As in FIG. 3 and FIG. 5, the zigzag cantilevers serve as springs tocushion the stress due to temperature variations and bending. FIG. 8shows the side view of FIG. 7. The chip 20 is sealed in glue 23 up to aportion of the zigzag cantilevers. The bottoms of the unsealed portionsL3 and R3 of the metallic plates 41, 42 serve as contacts for surfacemounting the package to a motherboard.

[0022]FIG. 9 shows the top view of a fourth embodiment of the presentinvention. The diode chip 50 has a top electrode and a bottom electrode,unlike the chip 20 in previous embodiments with two bottom electrodes.The diode chip 50 is mounted on a metallic plate 52. The top electrodeof diode chip 50 is wire-bonded by wire 56 to the second metallic plate51, as shown in side view FIG. 10. As in previous first and secondembodiments, metallic plates 51 and 52 have cuts 55 to form horizontalzigzag cantilevers. The zigzag cantilevers serve as springs to cushionthe stress due to temperature variations and bending. The chip 50 issealed in glue 23 up to a portion a portion of the zigzag cantilevers.The bottoms of the unsealed portions L4 and R4 of the metallic plates 51and 52 respectively serve as contacts for surface mounting the packagethe package to a motherboard.

[0023] While the preferred embodiments of the invention have beendescribed, it will be apparent to those skilled in the art that variousmodifications may be made in the embodiments without departing from thespirit of the present invention. Such modifications are all within thescope of this invention.

1. A surface mount semiconductor device package, comprising; asemiconductor device; and at least two metallic plates on which saidsemiconductor device is mounted, said metallic plates having bottomcontacts for surface mounting to a motherboard and zigzag cantileversfor making connections to said semiconductor device.
 2. A surface mountsemiconductor device package as described in claim 1, wherein saidsemiconductor device is a diode.
 3. A surface mount semiconductor devicepackage as described in claim 2, wherein said zigzag cantilevers arehorizontal.
 4. A surface mount semiconductor device package as describedin claim 3, wherein said zigzag cantilevers are of inverted-U shape. 5.A surface mount semiconductor device package as described in claim 3,wherein said zigzag cantilevers are of inverted-V shape.
 6. A surfacemount semiconductor device package as described in claim 2, wherein saidzigzag cantilevers are vertical.
 7. A surface mount semiconductor devicepackage as described in claim 1, further comprising a glue to seal saidsemiconductor device.
 8. A surface mount semiconductor device package asdescribed in claim 2, wherein said diode has two bottom electrodes.
 9. Asurface mount semiconductor device as described in claim 2, wherein saiddiode has a top electrode and a bottom electrode.
 10. A surface mountsemiconductor device as described in claim 9, wherein said bottomelectrode rests on the first plate of said metallic plates and said topelectrode is wire-bonded to the second plate of said metallic plates.